Interleukin-8 (IL-8) was discovered in the culture supernatant of monocytes stimulated with lipopolysaccharide (LPS), and is a chemokine known also as monocyte-derived neutrophil chemotactic factor (MDNCF) or neutrophil activating protein-1 (NAP-1). IL-8 is produced by various cells, acts on polymorphonuclear leukocytes and lymphocytes, and possesses activity that causes chemotaxis along its concentration gradient. In addition, not only does it induce chemotaxis in neutrophils, but it also activates neutrophilic functions such as degranulation, the release of superoxide, and the promotion of adhesion to endothelial cells.
In inflammatory diseases, and more specifically in respiratory diseases such as pulmonary cystic fibrosis, idiopathic pulmonary fibrosis, adult respiratory distress syndrome, sarcoidosis and empyema, as well as in skin diseases such as psoriasis, and in chronic rheumatoid arthritis, Crohn's disease and ulcerative colitis, leukocyte infiltration is observed pathologically at the inflamed site of these diseases. In addition, IL-8 is detected in test samples from patients with these diseases, suggesting that IL-8 may play a central role in inflammation. (McElvaney, N. G. et al., J. Clin. Invest., 90, 1296-1301, 1992; Lynch III, J. P. et al., Am. Rev. Respir. Dis., 145, 1433-1439, 1992; Donnelly, S. C. et al., Lancet, 341, 643-647, 1993; Car, B. D. et al., Am. J. Respir. Crit. Care Med., 149, 655-659, 1994; Antony, V. B. et al., J. Immunol., 151, 7216-7223, 1993; Takematsu, H. et al., Arch. Dermatol., 129, 74-80, 1993; Brennan, F. M. et al., Eur. J. Immunol., 20, 2141-2144, 1990; Izzo, R. S. et al., Scand. J. Gastroenterol., 28, 296-300, 1993; Izzo, R. S. et al., Am. J. Gastroenterol., 87, 1447-1452, 1992).
Subsequence to immunizing mice with human IL-8 as antigen, Ko, Y-C. et al. prepared the mouse monoclonal antibody WS-4 that binds to human IL-8 and inhibits the binding of human IL-8 to neutrophils as a result of that binding, namely that neutralizes the biological activity possessed by human IL-8. It has been clearly shown that the isotypes of mouse monoclonal antibody WS-4 consist of a .kappa.-type L chain and a C.gamma.l-type H chain (J. Immunol. Methods, 149, 227-235, 1992).
Known examples of antibodies against human IL-8 other than WS-4 include A.5.12.14 (Boylan, A. M. et al., J. Clin. Invest., 89, 1257-1267, 1992), the anti-Pep-1 antibody and anti-Pep-3 antibody disclosed in International Patent Application No. WO92-04372, and DM/C7 (Mulligan, M. S. et al., J. Immunol., 150, 5585-5595, 1993).
It was also found by administration of the mouse monoclonal antibody WS-4 into experimental models using rabbits that neutrophil infiltration is inhibited in pulmonary ischemic and reperfusion injury (Sekido, N. et al., Nature, 365, 654-657, 1993), LPS-induced dermatitis (Harada, A. et al., Internatl. Immunol., 5, 681-690, 1993) and LPS- or interleukin-1 (IL-1)-induced arthritis (Akahoshi, T. et al., Lymphokine Cytokine Res., 13, 113-116, 1994).
A homologue of human IL-8 exists in rabbits, and is referred to as rabbit IL-8. Since it has been clearly shown that the mouse monoclonal antibody WS-4 cross-reacts with rabbit IL-8, and that the antibody inhibits binding of rabbit IL-8 to rabbit neutrophils (Harada, A. et al., Internatl. Immunol., 5, 681-690, 1993), these findings suggest that anti-human IL-8 antibody would be useful as a therapeutic agent for the treatment of inflammatory diseases in humans.
Monoclonal antibodies originating in mammals other than humans exhibit a high degree of immunogenicity (also referred to as antigenicity) in humans. For this reason, even if mouse antibody is administered to humans, as a result of its being metabolized as a foreign substance, the half life of mouse antibody in humans is relatively short, thus preventing its anticipated effects from being adequately demonstrated. Moreover, human anti-mouse antibody that is produced in response to administered mouse antibody causes an immune response that is both uncomfortable and dangerous for the patient, examples of which include serum sickness or other allergic response. For this reason, mouse antibody cannot be administered frequently to humans.
In order to resolve these problems, a process for producing a humanized antibody was developed. Mouse antibody can be humanized by two methods. The simpler method involves producing a chimeric antibody in which the variable region (V region) is derived from the original mouse monoclonal antibody, and the constant region (C region) is derived from a suitable human antibody. Since the resulting chimeric antibody contains the variable region of the mouse antibody in its complete form, it has identical specificity to the original mouse antibody, and can be expected to bind to antigen.
Moreover, in the chimeric antibody, since the proportion of protein sequences derived from an animal other than human is substantially reduced in comparison to the original mouse antibody, it is predicted to have less immunogenicity in comparison to the original mouse antibody. Although the chimeric antibody binds well to antigen and has low immunogenicity, there is still the possibility of an immune response to the mouse variable region occurring, however (LoBuglio, A. F. et al., Proc. Natl. Acad. Sci. USA, 86, 4220-4224, 1989).
Although the second method for humanizing mouse antibody is more complex, the latent immunogenicity of the mouse antibody is reduced considerably. In this method, only the complementarity determining region (CDR) is grafted from the variable region of mouse antibody onto the human variable region to create a reshaped human variable region. However, in order to approximate more closely the structure of the CDR of the reshaped human variable region to the structure of the original mouse antibody, there are cases in which it may be necessary to graft a portion of the protein sequence of the framework region (FR) supporting the CDR from the variable region of the mouse antibody to the human variable region.
Next, these reshaped human variable regions are linked to the human constant region. Those portions derived from non-human protein sequences consist only of the CDR and a very slight portion of the FR in the humanized antibody. CDR is composed of hyper-variable protein sequences, and these do not exhibit species specificity. For this reason, the reshaped human antibody that contains the mouse CDRs ought not to have immunogenicity stronger than that of a natural human antibody containing human CDRs.
Additional details regarding reshaped human antibodies can be found by referring to Riechmann, L. et al., Nature, 332, 323-327, 1988; Verhoeyen, M. et al., Science, 239, 1534-1536, 1988; Kettleborough, C. A. et al., Protein Eng., 4, 773-783, 1991; Maeda, H. et al., Hum. Antibodies Hybridomas, 2, 124-134, 1991; Gorman, S. D. et al., Proc. Natl. Acad. Sci. USA, 88, 4181-4185, 1991; Tempest, P. R. et al., Bio/Technology, 9, 266-271, 1991; Co, M. S. et al., Proc. Natl. Acad. Sci. USA, 88, 2869-2873, 1991; Carter, P. et al., Proc. Natl. Acad. Sci. USA, 89, 4285-4289, 1992; Co, M. S. et al., J. Immunol., 148, 1149-1154, 1992; and, Sato, K. et al., Cancer Res., 53, 851-856, 1993.